1. Field of the Invention
This invention relates to the technical field of motor vehicle openings and in particular the tailgates of such motor vehicles.
2. Description of the Related Art
A motor vehicle tailgate is generally firstly pivotably mounted on a body of this vehicle, between an open position and a closed position, and secondly connected to this body by means that generate an axial thrust for assisting with the opening of the tailgate.
In closed position, the tailgate is generally intended to block a fixed rear opening of the body.
The means for hinging the tailgate on the body generally comprise a pair of hinges connecting firstly an upper edge of the opening and, secondly, an upper edge of the tailgate, and forming a horizontal hinge axis.
The means for assisting with the opening of the tailgate, which also help to cushion the tailgate closing movement, generally comprise at least one gas cylinder, generally two gas cylinders, one on the left and one on the right. Each gas cylinder is provided with a first end for connection with the body, in particular with a side edge of the rear opening, and a second end for connection with the tailgate, in particular with a side edge of the tailgate, so as to exert an axial thrust between these two connection ends.
The tailgate is held locked in closed position by additional means forming a lock arranged on this tailgate and the body.
A seal carried by the body or the tailgate is generally inserted and compressed between the tailgate in closed position and the body.
A motor vehicle tailgate of the “all plastic” type already known in the prior art comprises a plastic box (arranged on the inside of the vehicle when the tailgate is in closed position) and a plastic panel (arranged on the outside of the vehicle when the tailgate is in closed position). If necessary, a glass forming a rear window is carried by the panel.
The box and the panel can be made more particularly of thermoplastic materials. They are assembled together in particular by bonding.
In the case of a tailgate comprising components made of thermoplastic materials, we observe, under the effect of various mechanical and thermal stresses, the appearance of deformations of the tailgate panel (when the tailgate is in closed position).
More particularly, in some configurations connecting the ends of the assistance gas cylinders with the tailgate and the body, we observe the appearance of alignment faults of the tailgate with the complementary contour of the rear opening of the body, these alignment faults being located, considering the tailgate in closed position, in areas of the tailgate close to the side ends (left and right) of its upper edge. The appearance of alignment faults in the side ends (left and right) of the upper edge of the tailgate leads, firstly, to swelling towards the top of the part of the upper edge of the tailgate extending between the hinges, and secondly, the appearance of a clearance fault between the lower edge of the tailgate and the complementary contour of the rear opening of the body.
The mechanical stresses tending to produce these faults are generated in particular by the tailgate hinge and anchor points on the body, the seal compressed between the body and the tailgate (when the latter is in closed position) and the gas cylinders assisting with the opening of the tailgate which continue to exert their axial thrust when this tailgate is in closed position. We observe that the axial thrust of the gas cylinders, when the tailgate is in closed position, are largely responsible for the tailgate panel alignment faults.